As a result of continuing advances in computer graphics, images that look more and more realistic are being rendered in applications such as video games. A key to achieving a convincing image is the ability to realistically simulate lighting and shadowing effects on a textured (e.g., three-dimensional) surface.
One technique for rendering surface textures involves the use of normal maps. When rendering using normal maps, each point on a surface to be rendered is associated with a unit length vector that is perpendicular to that point. The normal vector indicates the direction that the surface is facing at that point. Using a normal map, contemporary graphics engines can render very complex looking surfaces to achieve a more realistic effect.
A normal map can contain a large quantity of data, especially when realistic-looking surfaces at high screen (display) resolutions are being portrayed. Compression schemes are usually employed to reduce the amount of data. However, conventional real-time compression techniques can result in a loss of precision when the data are reconstructed, leading to reduced image quality.